| edema | <clinical sign> The presence of abnormally large amounts of fluid in the intercellular tissue spaces of the body, usually applied to demonstrable accumulation of excessive fluid in the subcutaneous tissues. Oedema may be localised, due to venous or lymphatic obstruction or to increased vascular permeability or it may be systemic due to heart failure or renal disease. Collections of oedema fluid are designated according to the site, for example ascites (peritoneal cavity), hydrothorax (pleural cavity) and hydropericardium (pericardial sac). Massive generalised oedema is called anasarca. Origin: Gr. Oide ma = swelling (18 Nov 1997) |
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| edema, cardiac | A manifestation of congestive heart failure caused by increased venous and capillary pressures and often associated with the retention of sodium by the kidneys. (12 Dec 1998) |
| invisible | Incapable of being seen; not perceptible by vision; not visible. "To us invisible, or dimly seen In these thy lowest works. <zoology> " (Milton) Invisible bird, a small, shy singing bird (Myadestes sibilons), of St. Vincent Islands. Invisible green, a very dark shade of green, approaching to black, and liable to be mistaken for it. Origin: F. Invisible, L. Invisibilis. See In- not, and Visible. Source: Websters Dictionary (01 Mar 1998) |
| invisible differentiation | Differentiation of the cellular chemical constituents in the embryo prior to cytodifferentiation; sometimes recognizable histochemically. Synonym: invisible differentiation. (05 Mar 2000) |
| invisible spectrum | The radiation lying on either side of visible light, i.e., infrared and ultraviolet light. (05 Mar 2000) |